Abstract This work presents a tribological evaluation of the influence of graphite and bronze fillers in two commercial composites in a dry sliding pin-on-disc test at the same contact severity ( parameter) and four testing conditions (varying both normal force and sliding velocity). Both fillers, in comparison to pure PTFE, significantly affected the coefficient of friction (COF) and the mass loss. The sliding distance required to reach steady-state for COF was statistically equal for all three materials. The COF experienced a relevant influence of both normal force and sliding velocity. The graphite filler acted as a solid lubricant and exhibited reductions in COF (∼27% on average) and in mass loss (∼4.2 times lower on average). The bronze filler, on the other hand, had a COF increase of up to 5% for conditions with lower normal force but showed a significant reduction on the specific mass loss (∼5.3 times lower on average). Due to its higher thermal conductivity, the composite filled with graphite presented lower tribosystem temperatures in thermography evaluations. Good agreement of the temperature data was found considering a model that proposes the rate of heat generated by friction. With respect to wear of the composites, evidence of adhesion (transfer films to the counterface) and abrasive (microploughing and microcutting) wear mechanisms was found, in addition to the identification of preferential wear.

中文翻译：

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石墨和青铜填料对 PTFE 摩擦学行为的影响：商业材料评估

摘要 本工作在相同的接触强度（参数）和四种测试条件（不同的法向力和滑动速度）下，对两种商业复合材料中石墨和青铜填料的摩擦学影响进行了摩擦学评估。 . 与纯 PTFE 相比，两种填料都显着影响了摩擦系数 (COF) 和质量损失。对于所有三种材料，达到 COF 稳态所需的滑动距离在统计上是相等的。COF 受到法向力和滑动速度的相关影响。石墨填料充当固体润滑剂，并表现出降低 COF（平均约 27%）和质量损失（平均降低约 4.2 倍）。另一方面，青铜填料，在法向力较低的条件下，COF 增加高达 5%，但比质量损失显着降低（平均降低约 5.3 倍）。由于其较高的热导率，填充石墨的复合材料在热成像评估中表现出较低的摩擦系统温度。考虑到提出摩擦产生的热量的模型，发现温度数据具有良好的一致性。关于复合材料的磨损，除了确定优先磨损外，还发现了粘附（转移膜到配合面）和磨料（微犁和微切削）磨损机制的证据。在热成像评估中，填充石墨的复合材料具有较低的摩擦系统温度。考虑到提出摩擦产生的热量的模型，发现温度数据具有良好的一致性。关于复合材料的磨损，除了确定优先磨损外，还发现了粘附（转移膜到配合面）和磨料（微犁和微切削）磨损机制的证据。在热成像评估中，填充石墨的复合材料具有较低的摩擦系统温度。考虑到提出摩擦产生的热量的模型，发现温度数据具有良好的一致性。关于复合材料的磨损，除了确定优先磨损外，还发现了粘附（转移膜到配合面）和磨料（微犁和微切削）磨损机制的证据。